Start of USB host API

[tannewt]

This allows you to list and explore connected USB devices. It
only stubs out the methods to communicate to endpoints. That will
come in a follow up once TinyUSB has it. (It's in progress.)

Related to #5986

[tannewt]

The last build was mostly network failures and one size failure that seems to be unrelated. Please review and I'll likely need to do some tweaks that will lead to another CI run.

[dhalbert]

I didn't verify the i.MX stuff, though I did look it over. That's what your testing is doing.

Mostly some arg validation stuff. You could make these explicitly called-out TODO's if you don't have time.

Thanks for cleaning up and generalizing the debug UART stuff!

[dhalbert]

One board is not fitting.

[tannewt]

TinyUSB grew in size:

_usbd_rhport                                                      +1
dcd_mutex_def                                                     +2
dcd_mutex                                                         +4
usbd_int_set                                                     +20
storage_erase_filesystem                                          +8
complex_attr                                                      +2
osal_queue_send.isra.0                                           -16
edpt_dma_start                                                   +36
compile_decorated                                                 -4
mp_obj_exception_attr                                             +4
usbd_edpt_xfer.isra.0                                            +80
compile_atom_expr_normal                                          +4
tusb_hal_nrf_power_event                                          +4
mscd_xfer_cb                                                     +24
mp_qstr_const_attr                                                -4
usb_background                                                   -16
main                                                             +24
mp_qstr_const_pool                                                -8
_usbd_initialized                                                 -1

Total 258461 - 258297                                           +164

@jpconstantineu this disables the traceback module on the bluemicro833. It's new so I figured no code uses it. (Could do watchdog as an alternative.)

[dhalbert]

👍